The present invention is directed toward a method and apparatus for storing strip material. More specifically, the present invention is directed towards a method and apparatus for positioning a continuous strip of material onto a spool.
The present discussion is directed specifically towards the manufacture of strip material for building tires; however, the background art and the disclosed invention may also be applicable to other types of manufacturing wherein it is necessary to store strip material.
When forming a strip component, it may be desired to store the component in a manner that prevents the destruction or alteration of any preformed cross-sectional configuration. This is frequently accomplished by storing the component in a spiral spool storage device. The component is placed on a liner that is spirally wound inside the spool. Spacing between adjacent rows of spirally wound liner prevents the adjacent layers of wound material from contacting, thus preserving the preformed cross-sectional configuration of the strip component.
U.S. Pat. No. 5,412,132, JP 61-111261, and EP 621,124 illustrate such storage devices. U.S. Pat. No. 5,412,132 discloses a spool with stepped flanges wherein a liner of increasing width rests on the stepped flanges to support the component within the spool storage device. JP 61-111261 discloses a spool formed with protrusions for the edges of a liner to rest upon. EP 621,124 discloses a spiral spool storage device wherein the edges of the liner rest in continuous spiral grooves formed on the inner face of the spool flanges.
Because the space provided for the edges of the liner are of a relatively small dimension, the liner must be precisely fed to the storage spool. JP 61-111261 discloses first feeding the liner through a fixed metal plate. The plate has an arcuate shape with flanged sides causing the plate to have a width less than the width of the liner. The liner is fed through the plate, inside the flanges, reducing the effective width of the liner. After the liner passes through the plate, the liner is feed onto the spool prior. The liner returns to its original width after once it is placed onto the spool, known in the art as the liner xe2x80x9cpoppingxe2x80x9d into place.
EP 621,124 also teaches reducing the effective width of the liner prior to feeding it into position on the spiral spool. Three different methods of reducing the liner width are disclosed. Two methods employ the use of curved bars through which the liner passes. The curved bars are in a fixed angular relationship with the rod upon which the bars are attached. The third method disclosed employs two pairs of deflecting bars. The first pair initially deflects the edges of the liner and the second pair slides relative to the spiral spool to ensure proper positioning of the liner onto the spool.
While the above methods accomplish the goal of delivering the liner to the spiral spool, these methods require precise placement of the liner to prevent the liner from popping out of place, and to prevent folding and creasing. When such problems do occur with the liner, the continuous manufacturing of the component must be stopped to resolve the problem. The present invention is directed to a method of delivering the liner to the spiral spool in a manner and by an apparatus which overcomes these limitations and issues of the known delivery systems.
A self-aligning spool has an axis of rotation and is adapted for storing elastomeric components of a profiled cross-sectional shape. The spool has a circumferentially compliant liner for spirally wrapping about the axis. The liner has a pair of lateral edges. Separate from the liner is a pair of traction spacers. One traction spacer is located adjacent each lateral edge of the liner. Each traction spacer has a width and a thickness. The thickness of the traction spacer establishes the radial space between each spiral layer of the circumferentially compliant liner. Each traction spacer is a separate component of the spool and is provided in strips of material preferably radially compressible and circumferentially stretchable. Most preferably the traction spacers are elastomeric.
In the preferred embodiment the spool has at least one end having a perpendicular surface relative to the axis of rotation. The perpendicular surface of the at least one end provides a means to restrain lateral movement of the wound spool, its liner and associated strip applied to the liner.
A method for storing continuous lengths of formed strips of elastomeric components having a profile cross-sectional shape onto a storage spool is described.
The steps include placing the formed strip component on a liner having a pair of lateral ends and a pair of longitudinal ends, placing a traction spacer adjacent each lateral end of the liner, the traction spacers being strips having height or thickness slightly greater than the formed strips. The method further includes fixing a longitudinal end of the liner adjacent an axis of rotation of the spool, rotating the axis thereby winding the liner, the traction spacer and the strip into a spiral wherein the liner and the traction strip are radially supported by the traction spacers.
In the preferred method the additional step of restraining the lateral ends of the spool from lateral movement is provided for. The method further comprises the step of equalizing the diametrical dimension of each lateral end of the liner as the liner is being rotated to form the spiral. The step of equalizing the diametrical dimension of each lateral end includes the step of stretching the traction spacer of the lateral end having the larger diameter, thereby reducing the spacer thickness creating a reduced rate of diameter increase at one lateral end relative to the opposite end. The step of stretching the traction spacer on one lateral end more than the opposite lateral end is an automatic function whereby the torque applied to the traction spacers is greater at the larger diameter end thereby causing the strip to stretch and reduce its cross-sectional height or thickness automatically adjusting the diameter such that as the strip and spiral liner is wound the diameters are equalized and the torque generated approximates equal at each lateral end. Furthermore, the step of rotating the axis thereby winding the liner, traction spacer and formed strip component into a spiral includes the step of forming a substantially airtight pocket in which the formed strip component is positioned.